Field
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to an apparatus and method for optimizing resources on a Fractional Transmit Precoding Information Channel (F-TPICH).
Background
Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA). The UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks.
Uplink transmit diversity (ULTD) schemes employ more than one transmit antenna (usually two) at the UE to improve the uplink transmission performance, e.g., reduce the user equipment (UE) transmit power, or increase the UE coverage range, or increase the UE data rate, or the combination of the above. Improvements in the overall system capacity may also be seen. Based on the feedback requirements, ULTD schemes can be categorized into closed-loop (CL) and open-loop (OL) schemes. From the transmitter perspective, ULTD schemes can be classified as beamforming (BF) and antenna switching (AS) schemes.
In general, closed-loop (CL) transmit diversity (TD) schemes require the receiver to provide explicit feedback information about the spatial channel to assist the transmitter in choosing a transmission format over multiple transmit antennas. On the other hand, open loop (OL) TD schemes do not. In the context of the WCDMA uplink, the term OL TD schemes includes the schemes without introducing new feedback channels.
For the purpose of CL-ULTD, pre-coding information is fed back to a user equipment (UE) to support the beamforming operation. The problem then remains as to how to optimally utilize physical channel resources to transmit this information on the downlink in terms of channelization code and time slots.
Thus, aspects of this apparatus and method for optimally utilizing physical channel resources on an F-TPICH during CL-ULTD schemes.